Fig. 1. (A) Representative records of the isolated perfused Rana ridibunda heart electromechanical activity. Isolated hearts were perfused at either 25 or 42°C for up to 6 h with bicarbonate buffer pH 7.35, and the electrical as well as mechanical activity were monitored throughout using an appropriate setting as described in Materials and methods. (B) Time course of the mechanical activity (%) of the isolated perfused heart at the two different temperatures studied. ^*P<0.05 vs the respective value at time zero.